72977561 has 2 divisors, whose sum is σ = 72977562. Its totient is φ = 72977560.

The previous prime is 72977519. The next prime is 72977573. The reversal of 72977561 is 16577927.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66113161 + 6864400 = 8131^2 + 2620^2 .

It is an emirp because it is prime and its reverse (16577927) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 72977561 - 2¹⁰ = 72976537 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (72977761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36488780 + 36488781.

It is an arithmetic number, because the mean of its divisors is an integer number (36488781).

Almost surely, 2^72977561 is an apocalyptic number.

It is an amenable number.

72977561 is a deficient number, since it is larger than the sum of its proper divisors (1).

72977561 is an equidigital number, since it uses as much as digits as its factorization.

72977561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 185220, while the sum is 44.

The square root of 72977561 is about 8542.6905012414. The cubic root of 72977561 is about 417.8910932442.

The spelling of 72977561 in words is "seventy-two million, nine hundred seventy-seven thousand, five hundred sixty-one".